Thermal Evolution of the Structure of a Mg−Al−CO₃ Layered Double Hydroxide:  Sorption Reversibility Aspects

Abstract

In our prior study, we employed several in-situ techniques to investigate the thermal evolution of the structure of a Mg-Al-CO 3 layered double hydroxide (LDH) under an inert atmosphere and proposed a model to describe the structural evolution of the Mg-Al-CO 3 LDH structure. In this paper we present results of our ongoing investigations with these materials pertaining to their sorption characteristics and thermal reversibility under both inert and reactive atmospheres. The experimental observations are shown to be consistent with the structural model for the LDH previously proposed. The structure, sorption characteristics, and thermal reversibility of these materials are of importance in their use for the preparation of CO 2 -permselective membranes for high-temperature membrane reactor applications.

The Crucial Role of the K+–Aluminium Oxide Interaction in K+‐Promoted Alumina‐ and Hydrotalcite‐Based Materials for CO2 Sorption at High Temperatures

“…www.chemsuschem.org sorption band is observed at 1655 cm À1 for all samples which is typical of the OÀH bending mode of water. [25,[46][47][48] Accordingly, this band disappears after thermal treatment at temperatures over 100 8C and reappears after rehydration of the sample at room temperature (data not shown). Note at this point that this band might also hint at the presence of bicarbonate species at low temperature which are known to decompose at rather low temperatures.…”

Study of CO2 Diffusion and Adsorption on Calcined Layered Double Hydroxides: The Effect of Particle Size

“…The BPM assumption is consistent with the presence of a mesoporous region, as indicated by our BET measurements and by the TEM studies of the adsorbent particles. 19 In the intercrystalline porous region, diffusion is described by the following equations, 16…”

Temperature-Dependent Structure and Dynamics of Water Intercalated in Layered Double Hydroxides with Different Hydration States

“…Thermal decomposition studies of LDHs show dehydration and dehydroxylation occur sequentially upon heating. Generally, complete dehydration of intercalated water appears at 150–200 °C (423–473 K), but the brucite-like layered structure is still maintained. ,,− During the dehydration process as temperature increases, the intensity of the signal manifold in 27 Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra increases, which was ascribed to the increased mobility of water in interlayer galleries. , It probably implies water is less bound by layers at elevated temperature. However, how ice-like structures of confined water at ambient temperature vary as temperature increases is still not clear according to our knowledge.…”